In hemodialysis, hemofiltration, a cardiac surgery operation, etc., blood drawn from a patient is subjected to a predetermined treatment, and then the processed blood is returned to the patient. For this purpose, an extracorporeal circuit is formed to circulate blood outside the body with the use of a mechanical external force such as a pump. In the extracorporeal circuit, a coupling portion including a male connector and a female connector is used to connect tubes through which blood flows.
If the male connector and the female connector are unintentionally disconnected from each other during blood circulation, the blood that is forced to flow by a pump or the like will leak out and, in the worst case, may result in a serious accident such as patient's death from loss of blood.
Therefore, the coupling portion is provided with a lock mechanism for maintaining the connection between the male connector and the female connector to prevent such a serious accident. For example, Patent Documents 1 to 3 disclose a lever lock male connector. This male connector includes a male member and an elastically swingable lock lever. A claw is formed on the leading end of the lock lever and can be engaged with the female connector. The connection between the male connector and the female connector is maintained by engaging (locking) the claw with the female connector while the male member of the male connector is inserted into the female connector.
Moreover, the male connector and the female connector are provided with a mechanism for preventing leakage of blood to the outside even if the male connector and the female connector are unintentionally disconnected from each other. Patent Documents 4, 5 disclose a cover that is attached to the male member of the male connector. The cover is made of an elastic material such as rubber. A straight line-shaped slit (cut portion) is formed in the top of the cover. In the initial state, the male connector is not connected to the female connector, and the male member is housed in the cover. Therefore, the cover covers an opening of a flow channel at the leading end of the male member. When the male connector is connected to the female connector, the cover is compressively deformed in the longitudinal direction of the male member, and the leading end of the male member is inserted into the female connector through the slit of the cover. Thus, the male member and the female connector are in communication with each other, and blood can flow between them. In this state, if the male connector is unintentionally disconnected from the female connector, the cover immediately returns to the initial state, closes the slit, and covers the opening of the male member. Therefore, blood will not leak from the male member to the outside of the cover.
Incidentally, an operation called “priming” is performed before circulating blood in the extracorporeal circuit. The priming operation introduces a fluid (e.g., physiological saline, which is referred to as a “priming fluid” in the following) into a flow channel of the extracorporeal circuit, and discharges air in the flow channel to the outside. This is because if blood circulation is started with air present in the extracorporeal circuit, the air may enter the blood vessels of a patient and create critical health issues.
In order to prevent air in the extracorporeal circuit from flowing into a patient, the priming operation is performed before forming the extracorporeal circuit, i.e., in a state where the male connector and the female connector, which will constitute the coupling portion, are separated from each other. In this state, the flow channel in the male member of the male connector needs to be filled with the priming fluid.